heroes villains

I have a lot of problems with last night's season/fall finale of Heroes, most of which have already been discussed in Jason's review, in the comments section and elsewhere in the blogosphere. Why didn't Hiro freeze time again when he got into the vault with Adam? Why didn't Peter just stop time when Nathan was shot? Why was Nathan's press conference indoors when he was about to announce he could fly? What's the sense in killing Nathan and not Matt and Peter, when they can just show the world their powers? Why can't Hiro just go back in time to prevent Nathan from being killed, or why don't they just use Claire's blood (or Peter's?) to save him? And on and on and on it goes. I guess that's the problem of introducing time travel and immortality to a story. Anything can happen so it all seems ridiculous. Still, the show is a blast and I'll be back for the third volume.